1. Field of the Invention
This invention relates to the icing up of underwater intake gratings in cold water, and is directed more particularly to a reliable and economical system and method for monitoring ice build-up from a convenient remote location.
2. Description of the Prior Art
Industrial, commercial and municipal facilities located in regions subject to seasonal freezing, and which are required to draw quantities of water from rivers during the freezing seasons, are subject to the deleterious effects of buildup of frazil ice on gratings protecting water intakes from ingestion of foreign objects and aquatic life. The effects can include, depending on the nature of the facility in question, lower operating efficiencies, loss of cooling water, damage to pumps and other components, and loss of revenues because of down time.
"Frazil ice" is formed when turbulent water is cooled. Once the water is supercooled a few hundredths of a degree, minute ice crystals form in the water and conglomerate, resulting in flocks of frazil ice. Frazil ice forms mainly in rivers, but has been experienced in lakes, cooling ponds, and even in the ocean. Many water intakes for power generation plants and other industrial and commercial processing plants have waterway approaches that are subject to turbulent flow, a prime condition for the formation of frazil ice. As long as the water temperature is at, or below, freezing, it is possible for frazil ice to form. Once formed, frazil ice adheres to, and continues to accrete on, virtually any natural or man-made object in the water, including rocks, wood, and metal structures, and including protective gratings over water intakes. Water intakes have been known to completely occlude in a matter of a few hours.
Currently, the only detection and alarm systems in implementation consist of complex mechanical systems with moving components, having low reliability and requiring significant maintenance. There is thus a need for a simple, economical, reliable, and low maintenance system for detection and monitoring of growth of frazil ice on water intake gratings.